1. Field of the Invention
The invention relates to the use of oligo- and/or polysaccharides containing the sugar building block N-acylglucosamine and/or N-acylgalactosamine for the preparation of hemocompatible surfaces, methods for the hemocompatible coating of surfaces with said oligo- and/or polysaccharides as well as the use of the hemocompatibly coated surfaces.
2. Description of the Relevant Art
In the human body the blood gets in contact with surfaces other than the internal face of natural blood vessels only in case of an injury. Consequently the blood coagulation system is always activated to reduce the bleeding and to prevent a life-threatening loss of blood if blood gets in contact with foreign surfaces. Due to the fact that an implant also represents a foreign surface all patients receiving an implant which is permanently in contact with blood are treated for the duration of the blood contact with drugs, with so called anticoagulants which suppress the blood coagulation. This is also true for patients applicated an extracorporeal circulation such as hemodialysis patients. However this coagulation suppressive medication is in some extent afflicted with considerable side effects which range from loss of hair, nausea and vomitus beyond thrombocytopenia, hemorrhagic skin necroses and increased hemorrhagic diathesis up to side effects with a fatal outcome such as cerebral hemorrhages.
Thus there is a demand for non-thrombogenic, hemocompatible materials such as protheses, organ spareparts, membranes, cannulae, tubes, blood containers, stents etc. which do not activate the coagulation system in case of blood contact and do not cause coagulation of the blood.
EP-B-0 333 730 describes a method for preparation of hemocompatible substrates by incorporation, adhesion and/or modification and attachment of non-thrombogenic endothelial cell surface polysaccharide (HS-I). The immobilization of this specific endothelial cell surface proteoheparan sulphate HS I on biological or artificial surfaces causes that suchlike coated surfaces become blood compatible and suitable for the permanent blood contact. However, it is disadvantageous that said process for the generation of HS I requires the cultivation of endothelial cells, so that the economical usability of said process is very limited because the cultivation of endothelial cells is time consuming, and relatively large amounts of cultivated endothelial cells are only available at a considerably high cost.